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Olefin Metathesis / Grubbs Reaction Olefin Metathesis allows the exchange of substituents between different olefins - a PowerPoint Presentation
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Olefin Metathesis / Grubbs Reaction Olefin Metathesis allows the exchange of substituents between different olefins - a - PowerPoint PPT Presentation


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The Nobel Prize in Chemistry 2005 goes to Yves Chauvin , Robert H. Grubbs and Richard R. Schrock "for the develop -ment of the metathesis method in organic synthesis". Olefin Metathesis / Grubbs Reaction

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Presentation Transcript
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The Nobel Prize in Chemistry 2005 goes to Yves Chauvin, Robert H. Grubbs and Richard R. Schrock "for the develop -ment of the metathesis method in organic synthesis".

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Olefin Metathesis / Grubbs Reaction

Olefin Metathesis allows the exchange of substituents between different olefins - a transalkylidenation.

Synthetically useful, high-yield procedures for lab use include ring closure between terminal vinyl groups, cross metathesis - the intermolecular reaction of terminal vinyl groups - and ring opening of strained alkenes.

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Some new homogeneous catalysts which tolerate more functional groups and are more stable and easy to handle.

The Schrock catalysts are more active and are useful in the conversion of sterically demanding substrates, while the Grubbs catalysts tolerate a wide variety of functional groups.

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Mechanism

Initiation:

Catalytic Cycle:

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Ring Closing Metathesis (RCM)

The Ring-Closing Metathesis (RCM) allows synthesis of 5- up to 30-membered cyclic alkenes. The E/Z-selectivity depends on the ring strain. The Ru-catalysts are usually used.

Recent Literature

R. M. Conrad, M. J. Grogan, C. R. Bertozzi, Org. Lett., 2002, 4, 1359-1361.

B. Schmidt, Eur. J. Org. Chem., 2003, 816-819.

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Cross Metathesis

The transalkylidenation of two terminal alkenes under release of ethene, catalyzed by ruthenium carbenoids (Grubbs Catalyst).

Recent Literature

S. BouzBouz, R. Simmons, J. Cossy, Org. Lett., 2004, 6, 3465-3467.

K. Grela, M. Kim, Eur. J. Org. Chem., 2003, 963-966.

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Ring Opening Metathesis (Polymerization) - ROM(P)

Strained rings may be opened by a ruthenium carbene-catalyzed reaction with a second alkene following the mechanism of the Cross Metathesis. The driving force is the relief of ring strain. In absence of excess of a second reaction partner, polymerization occurs (ROMP):

Recent Literature

E. Arstad, A. G. M. Barrett, B. T. Hopkins, J. Koebberling, Org. Lett., 2002, 1975-1977.

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Reviews

  • M. Schuster and S. Blechert, Angew. Chem. Int. Ed. Engl.1997, 36, 2036
  • R. H. Grubbs and S. Chang, Tetrahedron1998, 54, 4413.
  • R. R. Schrock, Tetrahedron1999, 55, 8141.
  • R. R. Schrock and A. H. Hoveyda, Angew. Chem. Int. Ed. Engl.2003, 42, 4592.
  • A. Furstner, Angew. Chem. Int. Ed. Engl.2000, 39, 3012.